Adjustment mechanism for seating assembly member

ABSTRACT

A seating assembly having a seating assembly frame that includes a seat frame and a seatback frame. The seating assembly includes an extension member coupled to the seat frame and movable in response to an actuating force between an extended position relative to the seat frame and a compressed position relative to the seat frame and including an end fixedly coupled to the seat frame and an end coupled to an adjustment device disposed on the seat frame.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.17/201,098 filed Mar. 15, 2021, now U.S. Pat. No. 11,396,253 entitled“ADJUSTMENT MECHANISM FOR SEATING ASSEMBLY MEMBER.” The aforementionedrelated application is hereby incorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a seating assembly for avehicle.

BACKGROUND OF THE DISCLOSURE

Seating assemblies may include components that may move betweendifferent positions to accommodate different seating assembly needs.Improved movable components for seating assemblies are desired.

SUMMARY OF THE DISCLOSURE

According to a first aspect of the present disclosure, a seatingassembly is provided. The seating assembly includes a seating assemblyframe that includes a seat frame and a seatback frame. The seatingassembly further includes an extension member coupled to the seat frameand movable in response to an actuating force between an extendedposition relative to the seat frame and a compressed position relativeto the seat frame that includes an end fixedly coupled to the seatframe, and an end coupled to an adjustment device disposed on the seatframe.

Embodiments of the first aspect of the present disclosure can includeany one or a combination of the following features:

-   -   the adjustment device includes a guide member disposed at a rear        portion of the seat frame;    -   the extension member is movable between a primary position in        the guide member when the extension member is in the extended        position and a secondary position in the guide member when the        extension member is in the compressed position;    -   the end fixedly coupled to the seat frame is disposed along a        curved plate at a front portion of the seat frame;    -   the guide member includes an oblong structure having a channel        through which the extension member slides as the extension        member moves between the extended position and the compressed        position;    -   the adjustment device includes a bracket rotatably coupled to a        front portion of the seat frame and configured to receive an end        of the extension member;    -   the end of the extension member fixedly coupled to the seat        frame is disposed at a rear portion of the seat frame;    -   the bracket is rotatable about an axis of rotation extending        transverse to the extension member;    -   the bracket is rotatable between an initial position defined by        the extension member in the extended position and a final        position defined by the extension member in the compressed        position;    -   the bracket includes a stop member configured to abut a        structural component of a seat to limit rotation of the bracket        in the final position;    -   the structural component includes a seat leg;    -   the bracket includes a first link and a second link, wherein        each of the first link and the second link are pivotably coupled        to the seat frame at a pivotable coupling defined by the axis of        rotation, and wherein the first link and the second link each        extend outward from the pivotable coupling;    -   the extension member is coupled to the first link and wherein        the stop member is coupled to the second link; and/or    -   the actuating force includes a force exerted by a seatback on        the seat when the seatback is in a flat position.

According to a second aspect of the present disclosure, a vehicleseating assembly is provided. The vehicle seating assembly includes aseatback pivotably coupled to a seat and movable between an uprightposition and a folded position and includes a pair of extension memberseach coupled to front and rear portions of a seat frame and configuredto move from an extended position to a compressed position in responseto an actuating force disposed on the pair of extension members by theseatback in the folded position, and a pair of adjustment devicesdisposed on opposing lateral sides of the seat frame and at one of thefront or rear portions of the seat frame, wherein the pair of adjustmentdevices are coupled to the pair of extension members, wherein the pairof extension members in the extended position defines a pair ofbolsters.

Embodiments of the second aspect of the present disclosure can includeany one or a combination of the following features:

-   -   the pair of adjustment devices includes a pair of guides mounted        to the seat frame and wherein the pair of extension members        slides into each of the pair of guides in a first direction in        response to an application of the actuating force on the pair of        extension members and wherein the pair of extension members        slides out of each of the pair of guides in a second direction        in response to a removal of the actuating force from the pair of        extension members;    -   the pair of extension members includes bolster wires; and/or    -   the pair of adjustment devices includes a pair of brackets        disposed on opposing sides of the seat frame and pivotably        coupled to the seat frame at pivotable couplings defined by an        axis of rotation extending transverse to the pair of adjustment        devices and wherein the pair of extension members are coupled to        the pair of brackets such that application of an actuating force        on the pair of extension members in the extended position causes        the pair of brackets to rotate from an initial position to a        final position about the axis of rotation, thereby moving the        pair of extension members from the extended position to the        compressed position.

According to a third aspect of the present disclosure, a vehicle seat inprovided. The vehicle seat includes a seat frame that includes opposingfirst and second portions. The vehicle seat further includes anextension member extending between the first portion of the seat frameand the second portion of the seat frame and having an end fixedlycoupled to the first portion of the seat frame and an end rotatablycoupled to a rotating member disposed around a pivotable couplingdisposed on the second portion of the seat frame, wherein the rotatingmember disposed around the pivotable coupling is rotated between aninitial position and a final position as the extension member is movedbetween an extended position and a compressed position.

Embodiments of a third aspect of the present disclosure can include anyone or a combination of the following features:

-   -   the first portion of the seat frame includes a rear portion of        the seat frame, wherein the second portion of the seat frame        includes a front portion of the seat frame, and wherein the        extension member includes a bolster support.

These and other aspects, objects, and features of the present disclosurewill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a right side perspective view of a seating assembly withextension members in extended positions disposed in guide members,according to an aspect of the disclosure;

FIG. 2A is a right side elevational view of a seating assembly with anextension member disposed in a guide member in an extended position andthe extension member disposed in the guide member in a compressedposition, according to an aspect of the disclosure;

FIG. 2B is a right side elevational view of a guide member, according toan aspect of the disclosure;

FIG. 3 is a left side perspective view of a seating assembly withextension members in extended positions disposed in guide members,according to an aspect of the disclosure;

FIG. 4 is a right side perspective view of a portion of the seatingassembly with extension members in extended positions and brackets,according to an aspect of the disclosure;

FIG. 5 is a front perspective view of a portion of the seating assemblywith an extension member in the compressed position and a bracket,according to an aspect of the disclosure;

FIG. 6 is a right side elevational view of a seating assembly with aseatback in the folded position, an extension member in the compressedposition, and a bracket, according to an aspect of the disclosure;

FIG. 7 is a front perspective view of a portion of the seating assemblywith an extension member in the compressed position and a bracket,according to an aspect of the disclosure; and

FIG. 8 is a right side elevational view of a seating assembly with theseatback in an upright position and the extension member in the extendedposition and a seating assembly with the seatback in a folded position,according to an aspect of the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the vehicle seating assemblies 10 described below andshown in the attached figures, a vehicle seating assembly 10 may bedescribed from the vantage point of an occupant seated in the seatingassembly 10. The side of a seating assembly 10 disposed on a right sideof a seated occupant may be referred to as a right side of the seatingassembly 10. The side of the seating assembly 10 disposed on a left sideof a seated occupant may be referred to as a left side of the seatingassembly 10.

Referring to FIGS. 1-8 , a seating assembly 10 includes a seatingassembly frame 14. The seating assembly frame 14 includes a seat frame18 and seatback frame 22. An extension member 26 is coupled to the seatframe 18 and movable in response to an actuation force f between anextended position A relative to the seat frame 18 and a compressedposition B relative to the seat frame 18. The extension member 26includes an end fixedly coupled to the seat frame 18 and an end coupledto an adjustment device disposed on the seat frame 18.

Customers desire a vehicle that may be used for various purposes.Therefore, it is advantageous to configure vehicle seating assemblies 10to use vehicle space in multiple ways. A seating assembly 10 thatincludes extension members 26 may be configured in various ways. Theseating assembly 10 may include a seatback 54 and a seat 50 withextension members 26 that may define bolsters 42 of the seat 50.Bolsters 42 may stabilize the movement of a seated occupant duringvehicle use. The extension members 26 that define the bolsters 42 may bein an extended position A when the seatback 54 is in an upright positionE. The extension members 26 may be compressed as the seatback 54 movesfrom the upright position E to the folded position F to create the loadfloor 46. The extension members 26 may be in the compressed position Bwhen the seatback 54 is in the folded position F. As the seatingassembly 10 is moved from the folded position F to the upright positionE, the extension members 26 may move from the compressed position B tothe extended position A. In the extended position A, the extensionmembers 26 define the bolsters 42 that create a comfortable seatingspace for an occupant.

Referring to FIG. 1 , a seating assembly 10 may include a seatingassembly frame 14. The seating assembly frame 14 may include a seatframe 18 and a seatback frame 22. A seatback panel 66 may be disposed onthe back of the seatback frame 22. The seatback panel 66 may define theload floor 46 when the seatback 54 is in the folded position F. Theseatback panel 66 may provide support for a seatback cushion 62 disposedin the seatback frame 22. A tether 70 may be disposed in the seatbackpanel 66. A seat panel 68 may be positioned in the seat frame 18. Theseat panel 68 may provide support for a seat cushion 58 disposed abovethe seat panel 68. The seating assembly 10 may be mounted to a vehiclefloor 74 with rear mounts 78 and front mounts 82. Rear mounts 78 may bedisposed on opposing sides of a cross bar 86 extending proximate thebite line of the seat 50. The bite line may refer to the location atwhich the seat 50 and the seatback 54 come together. The seatingassembly 10 may include front mounts 82 positioned below a front portion94 of the seat frame 18. The front mounts 82 may include seat legs 98that may extend away from the seat frame 18 and toward the vehicle floor74.

With reference to FIGS. 1-3 , the seating assembly 10 may include a pairof opposing extension members 26 disposed on opposing sides of the seatframe 18. In the example shown, the seat frame 18 includes a pair ofopposing side brackets 102, a front cross member 106, and a rear crossmember 110. The seat frame 18 may include a front portion 94 and a rearportion 90. An end 30 of each of the extension members 26 may be fixedlycoupled to each of the opposing side brackets 102. An end 34 of each ofthe extension members 26 may be coupled to the adjustment devices 38disposed on each of the side brackets 102. In the example shown, theadjustment devices 38 may include guide members 38A. The guide members38A may be referred to as guides. The extension members 26 may bedisposed in the extended position A or the compressed position B. Thepair of extension members 26 may slide into the guide members 38A in afirst direction 114 in response to an application of an actuation forceF on the pair of extension members 26. The pair of extension members 26may slide out of the guide members 38A in a second direction 118 inresponse to the removal of the actuation force f. The extension members26 may be movable between a primary position I in the guide member 38Awhen the extension member 26 is in the extended position A and asecondary position J in the guide member 38A when the extension member26 is in the compressed position B. The fixed ends 30 of each of thepair of extension members 26 may be coupled to a front plate 122extending along the front cross member 106. Each of the pair ofextension members 26 may be disposed along the front plate 122. Thefront plate 122 may be curved. The front plate 122 may provide acomfortable surface for support of the calves of an occupant. The frontplate 122 may include an inward-extending portion 126 that may be curvedunder the seat 50.

With continued reference to FIGS. 1-3 , the guide members 38A may havean oblong structure. The guide members 38A may include an internalchannel 130 with a variable diameter 134. The diameter D1 of theinternal channel 130 at a location closer to the front portion 94 of theseat frame 18 may be greater than the diameter D2 of the internalchannel 130 at a location further from the front portion 94 of the seatframe 18. The variable diameter 134 between the location closer to thefront portion 94 of the seat frame 18 and the location further from thefront portion 94 of the seat frame 18 may direct the extension member 26downward and toward the seat when the extension member 26 moves from theextended position A to the compressed position B in response to anactuation force F. Additionally, the internal channel 130 may include anupper portion 138 extending along a downward slope 142 from the frontportion of the seat frame 18 to the rear portion 90 of the seat frame18. The downward slope 142 may be advantageous for compressing theextension member 26. It is to be understood that the guide members 38Amay have a structure other than the structure shown. For example, theguide members 34A may be integrated into the side brackets 102 of theseat frame 18 or other portions of the seat frame 18. The guide members38A may include guide sleeves.

With continued reference to FIGS. 1-3 , the extension member 26 may bemade of metal, composite, or another material. A metal extension member26 may include a spring steel. The extension member 26 may be stiff orflexible. The extension members 26 may include bolster wires that may bemade of steel. The bolster wires may also be made of a composite, acarbon fiber and epoxy resin mixture, or other materials. The materialof the guide members 34A and the material of the bolster wires may beselected to minimize friction between the guide members 34A and thebolster wires. The extension members 26 may include bolster supports.The internal channel 130 of the guide members 34A may be various shapes(for example, rectangular). The extension member 26 may have variousshapes (for example, rectangular) that may be compatible with theinternal channel 130.

Referring again to FIGS. 1-3 , the location of the pair of guide members34A and the pair of extension members 26 on the side brackets 102 of theseat frame 18 may be advantageous because the extension members 26 maybe disposed on the side brackets 102 prior to the attachment of the sidebrackets 102 to the front cross member 106 and the rear cross member 110during assembly of the seat frame 18. Additionally, the location of thepair of guide members 34A and the pair of extension members 26 on theside brackets 102 may form bolsters 42 on the sides of the seats 50 sothat the bolsters 42 may stabilize a seated occupant or cargo disposedon the seat 50.

With continuing reference to FIGS. 1-3 , the actuation force f exertedon the extension members 26 to move the extension members 26 from theextended position A to the compressed position B may include a forceexerted by cargo placed on the seat surface. The actuation force fexerted on the extension members 26 to move the extension members 26from the extended position A to the compressed position B may be theforce exerted by the seatback 54 on the seat 50 when the seatback 54 isin the folded position F. See, for example, FIGS. 6 and 8 .

Referring to FIGS. 4-8 , a vehicle seat 50 includes a seat frame 18having opposing first and second portions. The vehicle seat 50 includesan extension member 26 extending between the first portion of the seatframe 18 and the second portion of the seat frame 18. The extensionmember 26 has an end fixedly coupled to the first portion of the seatframe 18 and an end rotatably coupled to a rotating member 38B disposedaround a pivotable coupling 154 disposed on the second portion of theseat frame 18. The rotating member 38B is disposed around the pivotablecoupling 154 is rotatable between an initial position M and a finalposition N as the extension member 26 is moved between an extendedposition A and a compressed position B. If the rotating member 38B is inthe initial position M, then the seat legs 98 may be in the firstposition Q. If the rotating member 38B is in the final position N, thenthe seat legs 98 may be in the second position R. The seat legs 98 mayrotate about the axis of rotation 162 or another axis of rotationsubstantially parallel to axis of rotation 162 between the firstposition Q and the second position R of the seat legs 98. The seat legs98 may rotate about an axis of rotation 164 between the first position Qand the second position R of the seat legs 98. In the example shown, thefirst portion of the seat frame 18 may include a rear portion 90 of theseat frame 18, and the second portion of the seat frame 18 may include afront portion 94 of the seat frame 18. The extension member 26 mayinclude a flat strip. In the example shown, the rotating member 38Bincludes a bracket 150.

Referring to FIG. 4 , one end 30 of an extension member 26 may befixedly coupled to a rear portion 90 of the side bracket 102. Anotherend 34 of the extension member 26 may be fixedly coupled to a rotatingmember 38B disposed at a pivotable coupling 154 between the rotatingmember 38B and the side bracket 102. The rotating member 38B may includea bracket 150. The bracket 150 may be rotatable about an axis ofrotation 162 extending through the pivotable coupling 154 and the frontportion 94 of the seat frame 18. The axis of rotation 162 may betransverse to the extension member 26. In the example shown, the bracket150 includes first and second links 166, 170. The first and second links166, 170 each extend outward from the pivotable coupling 154. The firstlink 166 includes a pin 174. The extension member 26 may be coupled tothe pin 174. The second link 170 includes a pin 178. A flange 182 mayextend from the pin 178.

With continued reference to FIG. 4 , a flange 182 may extendtransversely away from the second link 170 and in a direction toward abottom of the seat 50. The flange 182 may abut a structural component ofthe seat 50 to limit rotation of the bracket 150 in the initial positionM and the final position N. In the example shown, the structuralcomponent includes a seat leg 98. The flange 182 may be referred to as astop member. In addition to the rectangular shape of the flange 182shown, the flange 182 may include a variety of other shapes,configurations, and structures. In various aspects of the disclosure,the flange 182 may be mounted on the seat leg 98 or another structure atsuch a position that the first link 166 or the second link 170 of thebracket 150 abuts the flange 182 in the initial position M and the finalposition N of the bracket 150 to generally limit rotation of the bracket150. The bracket 150 may be positioned on the side bracket 102 tominimize interference of the bracket 150 with a seated occupant and toprovide space for the bracket 150 to rotate. The extension member 26 isshown in the extended position A.

Referring to FIG. 5 , the bracket 150 is shown disposed on the outsideof the side bracket 102. The bracket 150 may be disposed adjacent to theside bracket 102. The bracket 150 may include a first link 166 and asecond link 170. A pin 174 may extend from the first link 166. Theextension member 26 may be disposed around the pin 174 extending fromthe first link 166. The extension member 26 may have several bends 190.The flat strip may be a metal, a composite, or an epoxy resin withcarbon fiber. A metal extension member 26 may include a spring steel.The second link 170 may include a pin 178 for securing the flange 182 tothe second link 170. The flange 182 may be disposed proximate the seatleg 98 of the seating assembly 10.

With continued reference to FIG. 5 , the bracket 150 may have a varietyof configurations and shapes in addition to the configuration and shapeshown. The bracket 150 including the first and second links 166, 170 maybe a unitary part. See, FIG. 6 . The bracket 150 including the first andsecond links 166, 170 may include separate parts, for example separatefirst link 166 and second link 170. The bracket 150 may have a roundedshape.

Referring to FIG. 6 , the seating assembly 10 is shown with the seatback54 in the folded position F. In the folded position F, the seatbackpanel 66 may function as a load floor 46 on which cargo may be disposed.If the seatback 54 is in a folded position F, the seatback 54 may exertan actuation force f on the seat 50 to move the extension members 26from the extended position A to the compressed position B, therebymoving the bracket 150 from the initial position M to the final positionN. In one example, the seatback frame 22 may be disposed substantiallyparallel to the seat frame 18 in the folded position F. The flange 182may be disposed against the seat leg 98 when the bracket 150 is in theinitial position M and the final position N.

With reference to FIG. 7 , the flange 182 is shown disposed against theseat leg++.

Referring to FIG. 8 , the seating assembly 10 may be positioned with theseatback 54 in an upright position E and the seatback 54 in a foldedposition F. The extension member 26 may be positioned in an extendedposition A and a compressed position B. The bracket 150 may bepositioned in an initial position M and a final position N.

Referring to FIGS. 1-8 , a vehicle seating assembly 10 may include aseatback 54 pivotably coupled to a seat 50 and movable between anupright position E and a folded position F. The seating assembly 10 mayinclude a pair of extension members 26 each coupled to front and rearportions 94, 90 of the seat frame 18 and configured to move from anextended position A to a compressed position B in response to anactuation force f disposed on the pair of extension members 26. Theseating assembly 10 may include a pair of adjustment devices 34 disposedon opposing lateral sides of the seat frame 18 and at one of the frontor rear portions 94, 90 of the seat frame 18. The pair of adjustmentdevices 34 may be coupled to the pair of extension members 26.

With reference to FIGS. 1-8 , it is to be understood that the extensionmembers 26 may be biased in a variety of ways to return to the extendedposition A from the compressed position B upon removal of the actuationforce f Additionally, an adjustment device 38 may include a biasingmechanism that may store energy when the extension member 26 moves froman extended position A to a compressed position B and that may releaseenergy when the extension member 26 moves from a compressed position Bto an extended position A.

With reference to FIGS. 1-8 , it is be understood that powered actuationmay be used to move an extension member 26 between an extended positionA and a compressed position B. A power actuator for moving an extensionmember 26 between an extended position A and a compressed positon mayinclude a cable actuator. Powered actuation may be used to move anextension member 26 between a compressed position B and an extendedposition A. A power actuator for moving an extension member 26 between acompressed position B and an extended position A may include a cableactuator.

It is to be understood that the extension members 26 may have differentcross-sectional areas and shapes along their lengths. The extensionmembers 26 may include segments of various materials and sizes.

It is to be understood that extension members 26 and adjustment devices34 may be positioned on the seat frame 18 in various orientations. Forexample, an extension member and an adjustment device may be positionedlaterally across the seat frame to create a lateral bolster.Additionally, an extension member and an adjustment device may bepositioned diagonally across the seat frame to create a diagonalbolster.

It is to be understood that extension members 26 and adjustment devices34 may be positioned on the seatback frame 22 in various orientations.For example, an extension member and an adjustment device may bepositioned longitudinally along the seatback frame to create alongitudinal bolster. An extension member and an adjustment device maybe positioned laterally across the seatback frame to create a lateralbolster. Additionally, an extension member and an adjustment device maybe positioned diagonally across the seatback frame to create a diagonalbolster.

A variety of advantages may be obtained by use of the presentdisclosure. Extension members 26 and adjustment devices 34 may beincorporated into a seating assembly frame 14 to allow for varying thesizes of bolsters 42. Movement of the extension members 26 to acompressed position B when an actuation force f is disposed on theextension members 26 may allow for a seatback 54 to form a flat loadfloor 46 when the seatback 54 is in the folded position F. Utilizationof the seating assembly 10 with the extension members 26 in the extendedposition A may provide comfort and support to an occupant of the seatingassembly 10.

Aspects of the present disclosure are also disclosed in co-pending,commonly assigned to Ford Global Technologies, LLC application 84312780entitled Support Assembly for Seating Assembly, the entire disclosure ofwhich is hereby incorporated herein by reference.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent disclosure, and further it is to be understood that suchconcepts are intended to be covered by the following claims unless theseclaims by their language expressly state otherwise.

What is claimed is:
 1. A seating assembly comprising: a seating assemblyframe including: a seat frame; and a seatback frame; an extension membercoupled to the seat frame and movable in response to an actuating forcebetween an extended position relative to the seat frame and a compressedposition relative to the seat frame and including: an end fixedlycoupled to the seat frame; and an end coupled to an adjustment devicedisposed on the seat frame, wherein the adjustment device includes aguide member disposed at a rear portion of the seat frame.
 2. Theseating assembly of claim 1, wherein the extension member is movablebetween a primary position in the guide member when the extension memberis in the extended position and a secondary position in the guide memberwhen the extension member is in the compressed position.
 3. The seatingassembly of claim 2, wherein the end fixedly coupled to the seat frameis disposed along a curved plate at a front portion of the seat frame.4. The seating assembly of claim 3, wherein the guide member includes anoblong structure having a channel through which the extension memberslides as the extension member moves between the extended position andthe compressed position.
 5. A vehicle seating assembly comprising: aseatback pivotably coupled to a seat and movable between an uprightposition and a folded position and including: a pair of extensionmembers each coupled to front and rear portions of a seat frame andconfigured to move from an extended position to a compressed position inresponse to an actuating force disposed on the pair of extension membersby the seatback in the folded position; a pair of adjustment devicesdisposed on opposing lateral sides of the seat frame and at one of thefront or rear portions of the seat frame, wherein the pair of adjustmentdevices are coupled to the pair of extension members, wherein the pairof extension members in the extended position defines a pair ofbolsters.
 6. The vehicle seating assembly of claim 5, wherein the pairof adjustment devices includes a pair of guides mounted to the seatframe and wherein the pair of extension members slides into each of thepair of guides in a first direction in response to an application of theactuating force on the pair of extension members and wherein the pair ofextension members slides out of each of the pair of guides in a seconddirection in response to a removal of the actuating force from the pairof extension members.
 7. The vehicle seating assembly of claim 6,wherein the pair of extension members includes bolster wires.
 8. Thevehicle seating assembly comprising a seating assembly frame including:a seat frame; and a seatback frame; an extension member coupled to theseat frame and movable in response to an actuating force between anextended position relative to the seat frame and a compressed positionrelative to the seat frame and including: an end fixedly coupled to theseat frame; and an end coupled to an adjustment device disposed on theseat frame, wherein the adjustment device includes a guide memberdisposed at a rear portion of the seat frame, wherein the extensionmember is movable between a primary position in the guide member whenthe extension member is in the extended position and a secondaryposition in the guide member when the extension member is in thecompressed position, and wherein the end fixedly coupled to the seatframe is disposed along a curved plate at a front portion of the seatframe.
 9. The vehicle seating assembly of claim 8, wherein the guidemember includes an oblong structure having a channel through which theextension member slides as the extension member moves between theextended position and the compressed position.